The aggregation-promoting factor of Lactobacillus crispatus M247 and its genetic locus

Area of Science:

• Microbiology
• Molecular Biology
• Probiotics

Background:

• Lactobacillus crispatus M247 is a human intestinal isolate known for aggregation.
• Aggregation is an important characteristic for probiotic bacteria.
• The aggregation-promoting factor (APF) is implicated in Lactobacillus aggregation.

Purpose of the Study:

• To characterize the APF of Lactobacillus crispatus M247.
• To investigate the cause of non-aggregation in the homologous mutant Mu5.

Main Methods:

• Western blot analysis to detect APF protein.
• Gene sequencing of the apf gene in M247 and Mu5.
• Comparison of APF protein and gene sequences between the wild-type and mutant strains.

Main Results:

• A 28-kDa protein cross-reacting with anti-APF antiserum was detected in the supernatant of both M247 and Mu5.
• The apf genes in M247 and Mu5 were identical, 672 nucleotides long, encoding a 223-amino acid protein (24.0 kDa).
• The loss of aggregation in Mu5 is not due to a defect in APF secretion or mutation in the apf gene.

Conclusions:

• The APF protein and its gene are functional in the nonaggregating mutant Mu5.
• The mutation in Mu5 likely affects another molecule involved in aggregation, potentially a receptor for APF.
• Further research is needed to identify the specific molecule responsible for the aggregation defect in Mu5.